From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37980C433B4 for ; Wed, 14 Apr 2021 05:47:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 89E5C61249 for ; Wed, 14 Apr 2021 05:47:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 89E5C61249 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 18C516B0072; Wed, 14 Apr 2021 01:47:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 13D4D6B0073; Wed, 14 Apr 2021 01:47:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F20236B0074; Wed, 14 Apr 2021 01:47:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0250.hostedemail.com [216.40.44.250]) by kanga.kvack.org (Postfix) with ESMTP id D71736B0072 for ; Wed, 14 Apr 2021 01:47:33 -0400 (EDT) Received: from smtpin40.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 9892F824934B for ; Wed, 14 Apr 2021 05:47:33 +0000 (UTC) X-FDA: 78029890386.40.51AE26C Received: from mail-vs1-f48.google.com (mail-vs1-f48.google.com [209.85.217.48]) by imf20.hostedemail.com (Postfix) with ESMTP id 62184D2 for ; Wed, 14 Apr 2021 05:47:28 +0000 (UTC) Received: by mail-vs1-f48.google.com with SMTP id g20so9789396vst.2 for ; Tue, 13 Apr 2021 22:47:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=tVM5T7WD+9isttd9BfiogfhskbumHL+3BbGPYht13nQ=; b=jmASpZXaYtVDVAS0rSRFBxoRqNjXSAxuK/tHeNfdRXLkTUWuKy1PdBM5ZHS1vgrSZu DeXgCiGMZ0UvNtn6dMvT1DWS3CjwPTXC8XxNiK8MZW7gbPAMPmIskS2FzDH8crbCwWy8 XUsy0kp97jP968CKK2VVloEbSqCDPZl0V9PesHT50Gn9PD22mZSf98gVwyFC9g/oTB1D VtFztYKAaacC4Cms9+3wBVoCNI57iNyhoQOYFHm0e8sLpzGFqixlG5g2YD3ZErz8pUqd CymziIRcoD/STAkwKH/hjtb6P38EZTsrCvwLuPFIiaOzNKuTWXWXPl16hYtuk1Z3o7Nd 2KEA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc; bh=tVM5T7WD+9isttd9BfiogfhskbumHL+3BbGPYht13nQ=; b=oO74Fv/PJ8WdDOzFjAxcjYk22K255g9Zb1QH2iOA9QhOkt8KwYsJlAAf0gt0M348/F R8XaaxdTHTywHLnSVF6D94Iyzpwkqvwi4O0ggI2AvmE+bKOofImYT1dAKR/GAX3uV8JE 8CepOEPem8r9IioG9Xgmc2ztLWjnvubAPfbWPFB6zqkkpJAVNCJcnX+0ZAgK/GcFLiR/ x4yx7pb988SwZJF2alxOBU9h+bMidw9Qmh2ww52pPTkVn0aEeWjzTDgarcGlD3iqeZ24 JL3A5/106SsFyQQXK/utTeySx9aaAHY7YlKzq932c4lO29GJkvFRC8MG+KXGbVBl7iei zPjw== X-Gm-Message-State: AOAM533qEf+YMxZTrHo68kgE9mOz3ZvIz4n5sSU4Vv5ohSl28b5GjX6Y jT+nQCoh9g7FT527krbVKQvNaIKT4b0XOuKwwM2Uhw== X-Google-Smtp-Source: ABdhPJwUyuq5Fq6ZWADQ1wCKWabArk1S2Rv0hXbduq6NJ4GnWBcSmvdgqW11he9RBhqmVXU2OilGHXfwnHm+9ibrOYA= X-Received: by 2002:a67:71c6:: with SMTP id m189mr25897205vsc.12.1618379252321; Tue, 13 Apr 2021 22:47:32 -0700 (PDT) MIME-Version: 1.0 From: Jue Wang Date: Tue, 13 Apr 2021 22:47:21 -0700 Message-ID: Subject: Re: [PATCH 3/4] mce/copyin: fix to not SIGBUS when copying from user hits poison To: bp@alien8.de Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, luto@kernel.org, naoya.horiguchi@nec.com, tony.luck@intel.com, x86@kernel.org, yaoaili@kingsoft.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 62184D2 X-Stat-Signature: waxwp4tfa41xiuwxbzjhhjyfnend7k1e Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=mail-vs1-f48.google.com; client-ip=209.85.217.48 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618379248-277656 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000011, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, 13 Apr 2021 12:07:22 +0200, Petkov, Borislav wrote: >> KVM apparently passes a machine check into the guest. > Ah, there it is: > static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk) > { > send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, PAGE_SHIFT, tsk); > } This path is when EPT #PF finds accesses to a hwpoisoned page and sends SIGBUS to user space (KVM exits into user space) with the same semantic as if regular #PF found access to a hwpoisoned page. The KVM_X86_SET_MCE ioctl actually injects a machine check into the guest. We are in process to launch a product with MCE recovery capability in a KVM based virtualization product and plan to expand the scope of the application of it in the near future. > So what I'm missing with all this fun is, yeah, sure, we have this > facility out there but who's using it? Is anyone even using it at all? The in-memory database and analytical domain are definitely using it. A couple examples: SAP HANA - as we've tested and planned to launch as a strategic enterprise use case with MCE recovery capability in our product SQL server - https://support.microsoft.com/en-us/help/2967651/inf-sql-server-may-display-memory-corruption-and-recovery-errors Cheers, -Jue